Nippon Steel Corporation

Nippon Steel Sumitomo Metal Corporation

Toyota Jidosha Kabushiki Kaisha

Aisin Takaoka Co., Ltd.

Koichi Nishizawa

Masaaki Omodaka

Mikio Kawamura

Tsukasa Oyama

Shinichi Suzuki

Shigeru Hashimoto

Toshimasa Tomokiyo

Masaaki Kondo

Seiji Sugiyama

Masafumi Matsumoto

Yu Matsumoto

Yuki Ishiguro

Noboru Furuta

Makoto Kusama

Yasuhiro Mori

Takayuki Suzuki

Hideyuki Kai

Hiroshi Minehara

[Object] What is provided is a manufacturing method of a galvannealed steel sheet capable of further promoting alloying of zinc plating with the steel sheet. [Resolution Means] A manufacturing method of a galvannealed steel sheet, including: forming on a surface of a steel sheet after hot rolling and pickling which contains, by mass %, C: 0.001% to 0.350%, Si: 0.001% to 2.500% or P: 0.001% to 0.100%, or combination thereof, Mn: 0.10% to 3.00%, S: 0.001% to 0.010%, N: 0.0010% to 0.0065%, and sol. Al: 0.001% to 0.800% with a remainder being Fe and impurities, grooves having an opening surface width of 10 &#x3bc;m to 25 &#x3bc;m and a depth of 10 &#x3bc;m to 30 &#x3bc;m at intervals of 20 &#x3bc;m to 500 &#x3bc;m; cold rolling the steel sheet at a rolling reduction of 30% or more; reduction annealing the steel sheet after the cold rolling; immersing the steel sheet in a hot-dip galvanizing bath containing 0.10 mass % to 0.20 mass % of Al with a remainder consisting of Zn and optional components, and adhering a hot-dip galvanized layer to the surface of the steel sheet; and heating the steel sheet to which the hot-dip galvanized layer is adhered, and alloying the steel sheet with the hot-dip galvanized layer.

Manufacturing method of galvannealed steel sheet

A continuous hot-dip plating machine includes: a sink roll provided in a plating bath and configured to upwardly change a transfer direction of the steel strip; a first support roll provided in the plating bath and located above the sink roll, the first support roll being in contact with a first surface of the steel strip in contact with the sink roll; and a second support roll provided in the plating bath and located above the first support roll, the second support roll being in contact with a second surface of the steel strip opposite the first surface. A diameter of the first support roll, a diameter of the second support roll, and a vertical distance between a rotation axis of the first support roll and a rotation axis of the second support roll satisfy specific conditions.

Continuous hot-dip metal plating device and continuous hot-dip metal plating method

A method for cooling a steel strip, comprising jetting mist to a steel strip passing through a cooling installation such that an amount of mist jetted to the steel strip is smaller in an edge portion in a width direction of the steel strip than in a center portion, sucking at least part of mist jetted to the steel strip, and cooling the steel strip at a sheet-passing speed such that, during a period between start and end of cooling, a temperature of the steel strip is within a film boiling temperature range and a temperature of the edge portion in the width direction of the steel strip is equal to or higher than a temperature of the center portion in at least a range of &#x2154; or more from the upstream side in the sheet-passing direction of a total cooling length of the cooling installation.

Method for cooling steel strip and cooling apparatus

A flow regulating member of a hot dip coating tank which is able to suppress stir-up of bottom dross, characterized by being provided with flow regulating member horizontal plates which are respectively arranged horizontally from below two side end parts of a sink roll, which is arranged inside of a coating tank in a rotatable manner, toward outside directions of the sink roll and side members which are arranged at positions separated from the two ends of the sink roll, which extend upward from the end parts of the respective horizontal plates, and in which large numbers of dispersion holes are formed, the side members having an aperture ratio of 20 to 80%, and the dispersion holes having a hole diameter of 5 to 50 mm.

Flow regulating member of hot dip coating tank and continuous hot dip coating system

A flow regulating member of a hot dip coating tank which can suppress stir-up of bottom dross, characterized by being provided with horizontal plates which are respectively arranged horizontally from below two side end parts of a sink roll, which is arranged inside of a coating tank in a rotatable manner, toward outside directions of the sink roll and louvers which are arranged above from the end parts of the respective horizontal plates at positions separated from the two ends of the sink roll and which have flow direction changing members which are slanted so that their heights become gradually higher toward the wall surface sides of the coating tank.

A high-strength quenched formed article has a zinc plating layer which is formed at a post-quenching formed steel sheet surface, and which contains 30 g/mor more of a phase that contains 5% or more by mass but 30% or less by mass of Fe, and which also contains 0.15% or more by mass but less than 2% by mass of at least one of Al and Si in a separate fashion or a composite fashion, and contains Zn, which makes up substantially a rest portion of the zinc plating layer, and an inevitable impurity, wherein the high-strength quenched formed article has a high-strength portion having a post-quenching-formation tensile strength of 1000 MPa or more, and a low-strength portion having a post-quenching-formation tensile strength of 800 MPa or less.

High-strength press hardened article, and manufacturing method therefor

Growing community of inventors

Tokyo, Japan

Koichi Nishizawa